The present invention provides an assembly for use in connecting optical fibres.
The invention is particularly, but riot exclusively, applicable to the management and routing of optical fibres at joints therefor. Typically in telecommunications, such joints are provided where it is desired to distribute optical fibres to customers. At the joint, optical fibres leading from a main network may be connected to fibres leading to individual customer locations. Hereinafter, fibres from the main network will be described as being supplied along a primary cable and fibres leading to customer locations will be described as secondary fibres. However, such joints can be provided to connect optical fibres from two primary cables thereby increasing the total length of cable.
Such joints are usually provided under ground and may be accessed via a man-hole to enable connections and routing to be made.
Optical fibres may be provided in fibre units, or bundles, which may comprise a number of fibres extending along a tube.
Hereto, optical fibre bundles enter a joint along a primary cable and are separated. Typically, eight or twelve fibres are provided in a fibre unit, or bundle, and these optical fibres are managed and routed to housings, or splice trays, where they may be connected to secondary optical fibres leading to individual customers. An example of these housings or splice trays is disclosed in the applicant""s earlier application, EP-A-981775.
Each housing comprises one port into which fibres may be routed from a primary cable and a second port into which secondary fibres may be routed from customer locations. Alternatively, the housings can be used to connect fibres from two primary cables.
The present invention is particularly but not exclusively applicable to the routing of fibres from a primary cable to the housings or splice trays.
Hereto, it is known to use a guide device which guides optical fibres from an optical fibre bundle into respective housings. Such a prior art guide device is shown schematically in FIG. 9. A fibre bundle 100 containing, for example eight fibres, is separated from a primary cable (not shown) and inserted into the guide device 102 at inlet port 103. Optical fibres 104 extend out of the tube of the fibre bundle and may be separated into single or individual groups of optical fibres 106 which are distributed out of the guide device 102 at outlet ports 107 and into an associated housing 108 in a stack 110 of housings where connections to other optical fibres are made.
Generally, a primary cable contains more than one optical fibre bundle, for example, twelve bundles that may each contain eight optical fibres, making ninety-six optical fibres in total. Previously, two fibres were needed to allow communication at a customer locationxe2x80x94a first optical fibre transmits light and a second optical fibre receives light. Therefore, the exemplary primary cable having twelve fibre bundles with eight fibres in each may be connected to a joint for distribution to a maximum of forty-eight customer locations. Each customer is allocated at least one housing from which two secondary fibres lead to the customer location. As schematically shown in FIG. 9, eight fibres 104 of an optical fibre bundle 100 are separated into groups of two fibres 106, each group leading into a housing. Therefore, twelve of the prior art guide devices shown in FIG. 9 are provided for routing the optical fibres to the respective housings, each device being associated with four housings and each fibre bundle leading to a guide device.
Recently, single fibre circuits have been introduced in which a single fibre both transmits and receives light. In this case, only a single optical fibre need be guided to each of the housings. There is some difficulty in adopting single fibre circuits with the prior art arrangement shown in FIG. 9 since each guide device is provided with only four outlet ports and eight outlet ports are required to route eight fibres from an eight fibre bundle to eight housings. In this case, it is required to separate the fibres of the fibre bundle into two groups of four fibres, using a manifold device, and route each group to a guide device 102. This is disadvantageous because these manifold devices take up space in a joint and space is limited. Also, it is relatively time consuming to separate the fibres into groups prior to introducing the fibres into the guide devices.
The situation is further complicated since optical fibre bundles are often provided with twelve optical fibres and both single and two fibre circuits may be required.
In addition to the above disadvantages it is desirable to have greater flexibility for routing fibres to selected housings which is currently not available in the prior art.
It is an object of the present invention to provide an assembly for connecting optical fibres which is flexible and which can readily accommodate single and two fibre circuits.
The present invention provides an assembly for use in connecting optical fibres, the assembly comprising a plurality of housings for housing connections between optical fibres and a guide arrangement for guiding optical fibres into said housings, said guide arrangement comprising a plurality of guide devices mounted side-by-side, each guide device having at least one inlet port for the passage of optical fibres into the guide arrangement, at least one outlet port associated with a said housing for guiding optical fibres into the associated housing, at least one further inlet port for receiving optical fibres from another one of said guide devices when positioned adjacent said guide device on one side thereof and at least one further outlet port for guiding optical fibres to another one of said guide devices when positioned adjacent said guide device on another side thereof, said guide arrangement comprising at least two guide devices.
The or each inlet port may have a substantially cylindrical portion to correspond with the shape of a tubular member containing optical fibres so that a push-fit connection can be achieved by such a tubular member in the inlet port.
Each guide device may provide a plurality of fixed tracks extending from said at least one inlet port to said at least one outlet port and to said at least one further outlet port for guiding optical fibres from the or each inlet port to said at least one outlet port and to said at least one further outlet port.
Each guide device may provide a plurality of fixed tracks extending from said at least one further inlet port to said at least one outlet port and to said at least one further outlet port for guiding optical fibres from the or each further inlet port to said at least one outlet port and to said at least one further outlet port.
Said fixed tracks may be channels and have a bend radius not less than a predetermined distance for reducing signal attenuation in optical fibres disposed therein.
The further outlet ports of one of said guide devices may be adjacent the further inlet ports of another of said guide devices for guiding optical fibres between said one and said other guide devices.
Fixed tracks may provide tracks which extend from the or each inlet port of one of said devices to the outlet ports of another of said guide devices and said tracks have a bend radius not less than a predetermined distance for reducing signal attenuation in optical fibres disposed in the tracks.